Running low on oxygen, Air Force Staff Sgt. Shane Bedard felt tingling in his fingers. His vision blurred. Then came a sensation of euphoria.

Welcome to another day at the Aerospace and Operational Physiology unit at Langley Air Force Base, where a small group of specialists train pilots and parachutists to recognize the creeping symptoms of hypoxia, or oxygen deprivation.

The training has been around for years, but Langley personnel upgraded the system a few months ago and they're pleased with the results.

Bedard's experience took place in the safety of a darkened room in a building off the beaten path at Langley. As he sat with a heavy parachute strapped on his back for realism, Staff Sgt. John Crump slowly decreased the flow of oxygen to Bedard's mask.

The resulting symptoms -- tingling, blurred vision, euphoria -- show the danger of hypoxia, said Maj. Joseph Teodoro, who commands the Langley unit, which falls under the 633rd Medical Group.

Nausea and numbness are among the other symptoms, and euphoria isn't always part of the mix. A disoriented subject can get belligerent. That happened to Bedard in a previous training round.

Now he can smile at his aborted attempt to stab someone with a pen.

"He was trying to put my mask on me to save my life," he recalled. "I tried to stab him instead. That's probably not the appropriate thing to do."

The Langley team attracts Air Force pilots, Navy SEALS and Army Special Forces personnel for training and classroom instruction. They come to Langley because of scheduling conflicts at other bases, the need for a quick deployment or because they're here for other reasons.

Pilots who fly high-performance fighters and heavy cargo planes undergo the training. It also applies to those training to be high-altitude parachute jumpers, such as Bedard. He spent eight years in the Air Force and is now with the Air National Guard, stationed at Fairchild Air Force Base near Spokane, Wash.

Bedard is training to be a medic, which brought him to Langley's hospital. While here, he decided to keep his physiological training current.

One challenge of the hypoxia training is convincing people not to "tough it out," Teodoro said. The strongest war-fighters in the U.S. military walk though his door. They're taught to withstand pain and harsh conditions, but hypoxia can disable the toughest soldier, sailor, airman or Marine.

"It's not a competition to see who can last the longest without oxygen," Teodoro said.

In teaching classes, Teodoro keeps the mood light. He likes to describe some of the more outrageous examples of what happens during hypoxia training, such as an Army parachutist who stood up and tried to "jump" from his chair.

He says the humor makes people feel more comfortable. When they do, they might open up about times when they experienced hypoxia during a mission or in training.

"Mishaps are still happening," he said.

For years, the Langley unit used a "classic altitude chamber that's been around for decades," said Air Force Master Sgt. Isis Lovette. But it was complicated to operate and required several technicians to run it. The new system is simply called the Reduced Oxygen Breathing Device, and Lovette said she was glad to see it arrive.

Hypoxia made national headlines a few years ago when F-22 Raptor pilots experienced the symptoms while flying. The Air Force eventually figured out a solution. Teodoro said the Raptor got attention because it was a new aircraft.

"But the truth is," he said, "it's important for many aircraft and crew members."